Note - This info is based on Adobe Acrobat Reader version 5.1
- The memory problem has reportedly been fixed in version 7.

When viewing a .pdf document in Mozilla, Adobe Acrobat reader is invoked to
display the .pdf file in a browser window (or tab). However, when you
close that window or tab Acrobat Reader (Acrord32.exe) will remain in
memory. It is a process taking up approximately 30 Mb of memory. This
is an Acrobat Reader plugin and program problem.

One option is to open Task Manager and kill the process. Here's
another approach gleaned from the netscape.public.mozilla.browser
newsgroup. It will open Acrobat Reader outside of Mozilla to display
the document.

2. Search for nppdf32.dll using Windows Explorer on your hard drive(s).
Rename every instance of the file (e.g. rename to nppdf32.dll.bak).
This is important because Mozilla will find this wherever it is,
so you must delete or rename all instances.

3b. In Firefox there is no way to create a Helper definition. Try opening Tools - Options - Downloads and see if an
Adobe pdf helper exists. If so, click Change Action and make sure to check either Open in the Default Application (and
point it to the Adobe reader program) or select Save to Disk.

If that doesn't work then delete the Adobe helper, find a .pdf link (http://edmullen.net/mozilla/moz_filetest.php),
click on it and you should get a dialogue asking what to do with the .pdf file. Answer the dialogue and that will
create a new Helper definition.

4. Add a new helper as follows:

Mime type: application/pdf

Extension: pdf (no period)

Select "Open it with:" and click "Choose" to browse to the location of
the Acrobat Reader executable (usually something like C:\Program
Files\Adobe\Acrobat 5.0\Reader\)

Select the file: acrord23.exe.

You will need to restart Mozilla for this to take effect.

Once you're done it should look like these two screen shots. You can, of course, decide for yourself
whether to set to be prompted each time, or not.